Have humans re-shaped dog brains?
A recent study has demonstrated how humans have altered the shape of dog brains through centuries of domestic breeding.
There are hundreds of dog breeds with distinctive physical and behavioral characteristics as a result of centuries of selective breeding at the hands of humans. Although it seems obvious that these behavioral differences are a result of underlying neural differences, this has never actually been explored.
However, a recent study, published in The Journal of Neuroscience, has demonstrated how humans have not just altered the way that dogs look and behave but have actually altered the gross organization of dog brains.
Using MRI scans of dog brains, the team, led by Erin Hecht of Harvard University (MA, USA), assessed the regional volumetric variation in the brain of 62 male and female dogs representing 33 different breeds with varying behavioral specialisms.
- Spatial memory may determine mule deer migration routes
- The ancient canine cancer that has spread worldwide
- Examining enamel thickness in crocodile teeth
They discovered significant neuroanatomical variation across the different breeds. This variation was not randomly distributed and the researchers were able to identify six brain networks where regional volume covaried significantly across individuals.
Further analysis revealed that this variation in dog brain structure was not simply down to total brain size, total body shape or skull shape. Instead these variations appeared to correlate with different behavior characteristics such as sight hunting, scent hunting, guarding and companionship.
The researchers then went on the investigate the relationship between the covarying morphological components and the dog phylogenetic tree. They found that the majority of changes occurred on the terminal branches, suggesting that these changes have come about due to strong, recent selection in individual breeds.
The results of this study call into question the use of functional MRI in veterinary studies involving dogs, since this usually involves grouping together dogs of varying breeds which, as the study highlights, can have highly variable brain anatomy.
However, the implications of this study extend further than just studies involving dogs. Understanding the relationship between the brain and behavior and how learned behaviors evolve is applicable in a huge range of species, including humans.
If nothing else, the study has shone a light on the true effect that selective breeding has on a species. This provides a greater insight into the true impact that we, as a species, have on the wider animal kingdom.
